The role of echocardiography in the assessment of cardiac function in weightlessness-Our experience during parabolic flights.

Parabolic flight (PF) elicits changes in hydrostatic pressure gradients, resulting in increase (at 0Gz) or decrease (at 1.8Gz) in cardiac preload. The magnitude of these changes on left ventricular (LV) and atrial (LA) volumes, as well as on myocardial velocities, strain and strain rates, is largely unknown. Using real-time 3D (RT3DE) and Doppler tissue echocardiographic imaging (DTI) during PF in normal subjects in standing position, we showed that both LV and LA volumes were decreased at 1.8Gz and increased at 0Gz by about 20% and 40%, respectively. Previous 2D or M-mode studies underestimated such changes. Also, preload dependence was confirmed for systolic and diastolic velocities, and peak systolic strain, while strain rates were preload independent, probably reflecting intrinsic myocardial properties. Low body negative pressure at -50mmHg applied during 0Gz was effective in restoring 1Gz levels. RT3DE and DTI during PF are feasible, allowing the evaluation of the cardiac function under different loading conditions.

Combined assessment of myocardial perfusion and regional left ventricular function by analysis of contrast-enhanced power modulation images.

BACKGROUND: Echocardiographic contrast media have been used to assess myocardial perfusion and to enhance endocardial definition for improved assessment of left ventricular (LV) function. These methodologies, however, have been qualitative or have required extensive offline image analysis. Power modulation is a recently developed imaging technique that provides selective enhancement of microbubble-generated reflections. Our goal was to test the feasibility of using power modulation for combined quantitative assessment of myocardial perfusion and regional LV function in an animal model of acute ischemia. METHODS AND RESULTS: Coronary balloon occlusions were performed in 18 anesthetized pigs. Transthoracic power modulation images (Agilent 5500) were obtained during continuous intravenous infusion of the contrast agent Definity (DuPont) at baseline and during brief coronary occlusion and reperfusion and were analyzed with custom software. At each phase, myocardial perfusion was assessed by calculation, in 6 myocardial regions of interest, of mean pixel intensity and the rate of contrast replenishment after high-power ultrasound impulses. LV function was assessed by calculation of regional fractional area change from semiautomatically detected endocardial borders. All ischemic episodes caused detectable and reversible changes in perfusion and function. Perfusion defects, validated with fluorescent microspheres, were visualized in real time and confirmed by a significant decrease in pixel intensity in the left anterior descending coronary artery territory after balloon inflation and reduced rate of contrast replenishment. Fractional area change decreased significantly in ischemic segments and was restored with reperfusion. CONCLUSIONS: Power modulation allows simultaneous online assessment of myocardial perfusion and regional LV wall motion, which may improve the echocardiographic diagnosis of myocardial ischemia.

Quantitative assessment of regional right ventricular function with color kinesis.

We used color kinesis, a recent echocardiographic technique that provides regional information on the magnitude and timing of endocardial wall motion, to quantitatively assess regional right ventricular (RV) systolic and diastolic properties in 76 subjects who were divided into five groups, as follows: normal (n = 20), heart failure (n = 15), pressure/volume overload (n = 14), pressure overload (n = 12), and RV hypertrophy (n = 15). Quantitative segmental analysis of color kinesis images was used to obtain regional fractional area change (RFAC), which was displayed in the form of stacked histograms to determine patterns of endocardial wall motion. Time curves of integrated RFAC were used to objectively identify asynchrony of diastolic endocardial motion. When compared with normal subjects, patients with pressure overload or heart failure exhibited significantly decreased endocardial motion along the RV free wall. In the presence of mixed pressure/volume overload, the markedly increased ventricular septal motion compensated for decreased RV free wall motion. Diastolic endocardial wall motion was delayed in 17 of 72 segments (24%) in patients with RV pressure overload, and in 31 of 90 segments (34%) in patients with RV hypertrophy. Asynchrony of diastolic endocardial wall motion was greater in the latter group than in normal subjects (16% versus 10%: p < 0.01). Segmental analysis of color kinesis images allows quantitative assessment of regional RV systolic and diastolic properties.

Differences among geriatricians, general internists, and cardiologists in the care of patients with heart failure: a cautionary tale of quality assessment.

OBJECTIVES: To describe differences in the characteristics, processes of care, and resource utilization of patients with heart failure cared for by geriatricians, general internists, cardiologists, and combinations of physicians. DESIGN: A retrospective cohort study. SETTING: An urban academic medical center. PARTICIPANTS: A total of 439 outpatients with a billing diagnosis of heart failure or cardiomyopathy who were treated by geriatricians, general internists, cardiologists, and combinations of physicians. MEASUREMENTS: Demographic and clinical characteristics, medication use, diagnostic testing, hospitalizations, and inpatient and outpatient costs were measured. RESULTS: Compared with patients of cardiologists, patients cared for by geriatricians were older, more likely to have hypertension, diastolic dysfunction, and high comorbidity, and less likely to undergo echocardiography, cardiac catheterization, and electrocardiography. Use of angiotensin-converting enzyme inhibitors was similar among patients with reduced systolic function. Patients cared for by geriatricians had the same costs, rates of hospitalization, and likelihood of being symptomatic as patients of cardiologists. CONCLUSIONS: The processes of care for patients with heart failure seen solely by geriatricians differ from those for patients seen by other physicians, but the case-mix also varies. Assessment of left ventricular function by geriatricians probably needs to be increased. However, although they were older and had more comorbidity, patients of geriatricians had total costs and symptomatology similar to those of patients of cardiologists. Future work is needed to identify those patients most likely to benefit from treatment by geriatricians and to determine how care can be optimally coordinated among different types of physicians and health providers.

Assessment of small-diameter aortic mechanical prostheses: physiological relevance of the Doppler gradient, utility of flow augmentation, and limitations of orifice area estimation.

BACKGROUND: Noninvasive assessment of functionally stenotic small-diameter aortic mechanical prostheses is complicated by theoretical constraints relating to the hemodynamic relevance of Doppler-derived transprosthetic gradients. To establish the utility of Doppler echocardiography for evaluation of these valves, 20-mm Medtronic Hall and 19-mm St Jude prostheses were studied in vitro and in vivo. METHODS AND RESULTS: Relations between the orifice transprosthetic gradient (equivalent to Doppler), the downstream gradient in the zone of recovered pressure (equivalent to catheter), and fluid mechanical energy losses were examined in vitro. Pressure-flow relations across the 2 prostheses were evaluated by Doppler echocardiography in vivo. For both types of prosthesis in vitro, the orifice was higher than the downstream gradient (P<0.001), and fluid mechanical energy losses were as strongly correlated with orifice as with downstream pressure gradients (r2=0.99 for both). Orifice and downstream gradients were higher and fluid mechanical energy losses were larger for the St Jude than the Medtronic Hall valve (all P<0.001). Whereas estimated effective orifice areas for the 2 valves in vivo were not significantly different, model-independent dynamic analysis of pressure-flow relations revealed higher gradients for the St Jude than the Medtronic Hall valve at a given flow rate (P<0.05). CONCLUSIONS: Even in the presence of significant pressure recovery, the Doppler-derived gradient across small-diameter aortic mechanical prostheses does have hemodynamic relevance insofar as it reflects myocardial energy expenditure. Small differences in function between stenotic aortic mechanical prostheses, undetectable by conventional orifice area estimations, can be identified by dynamic Doppler echocardiographic analysis of pressure-flow relations.

Cor triatriatum in a 70-year-old woman: role of transesophageal echocardiography and dynamic three-dimensional echocardiography in diagnostic assessment.

In this report we describe a 70-year-old woman with unrecognized nonobstructive cor triatriatum (CT). She had concomitant mitral regurgitation and coronary artery disease. Diagnosis of CT and its hemodynamic assessment were accomplished by transesophageal echocardiography. Dynamic three-dimensional echocardiography demonstrated multiple fenestrations in the left atrial membrane. Intraoperative findings confirmed the diagnostic accuracy of three-dimensional echocardiography. To our knowledge, this is the first case of CT that has anatomic correlation with three-dimensional echocardiography.

Serial assessment of the cardiovascular system in normal pregnancy. Role of arterial compliance and pulsatile arterial load.

BACKGROUND: Temporal changes in systemic arterial compliance and wave propagation properties (pulsatile arterial load) and their role in ventricular-systemic arterial coupling during gestation have not been explored. Noninvasive methods combined with recently developed mathematical modeling techniques were used to characterize vascular and left ventricular (LV) mechanical adaptations during normal gestation. METHODS AND RESULTS: Fourteen healthy women were studied at each trimester of pregnancy and again postpartum. Experimental measurements included instantaneous aortic pressure (subclavian pulse tracings) and flow (aortic Doppler velocities) and echocardiographic imaging of the LV. A small increase in LV muscle mass and end-diastolic chamber dimension occurred by late gestation, with no significant alterations in myocardial contractility. Cardiac output increased and the steady component of arterial load (total vascular resistance) decreased during pregnancy. Several changes in pulsatile arterial load were noted: Global arterial compliance increased (approximately 30%) during the first trimester and remained elevated thereafter. The magnitude of peripheral wave reflections at the aorta was reduced. The mathematical model-based analysis revealed that peripheral wave reflections at the aorta were delayed and that both conduit and peripheral vessels contributed to the increased arterial compliance. Finally, coordinated changes in the pulsatile arterial load and LV properties were responsible for maintaining the efficiency of LV-to-arterial system energy transfer. CONCLUSIONS: The rapid time course of compliance changes and the involvement of both conduit and peripheral vessels are consistent with reduced vascular tone as being the main underlying mechanism. The pulsatile arterial load alterations during normal pregnancy are adaptive in that they help to accommodate the increased intravascular volume while maintaining the efficiency of ventricular-arterial coupling and diastolic perfusion pressure.

An echocardiographic approach to the assessment of aortic stenosis.

An accurate echocardiographic assessment of aortic stenosis is critical for the cost-effective diagnosis and management of patients with the clinical suspicion of this diagnosis. Although the concepts involved in the echocardiographic determination of aortic pressure gradients and valve areas are relatively simple, acquisition of the data required to perform these calculations can at times be technically challenging. After reviewing the clinical signs and symptoms and the hemodynamics of aortic stenosis, this article reviews in detail the technical aspects involved in obtaining accurate gradients and valve areas emphasizing potential pitfalls.

Noninvasive assessment of the direct action of oral nifedipine and nicardipine on left ventricular contractile state in patients with systemic hypertension: importance of reflex sympathetic responses.

OBJECTIVES: This study was designed to noninvasively assess the direct action of calcium channel blockers on left ventricular contractility in humans and to establish a framework for determining the importance of reflex sympathetic responses to any pharmacologic intervention. BACKGROUND: Assessment of left ventricular contractility in patients taking calcium channel blockers by using traditional indexes of systolic performance is difficult because of the after-load-reducing and reflex sympathetic effects of the drugs. METHODS: Fifteen hypertensive patients (mean blood pressure 127 +/- 15 mm Hg) were studied with Doppler echocardiography and calibrated subclavian pulse tracings while receiving placebo and 1 week after randomization to treatment with oral nifedipine (20 mg three times daily; n = 7) or nicardipine (30 mg three times daily; n = 8). Left ventricular circumferential end-systolic wall stress versus rate-corrected velocity of shortening (Vcfc) relations were generated over a range of loads using nitroprusside. Data were acquired before and during esmolol infusion, thereby allowing assessment of hemodynamic responses with the sympathetic nervous system functionally intact as well as ablated. The adequacy of sympathetic blockade was confirmed with isoproterenol challenges. In each case, left ventricular contractile state was measured relative to placebo and esmolol data as delta Vcfc at a common end-systolic wall stress. Increased and decreased contractility were defined as delta Vcfc > 0 and delta Vcfc < 0, respectively. RESULTS: Nifedipine and nicardipine equally decreased blood pressure and end-systolic wall stress and increased left ventricular percent fractional shortening and stroke volume. Neither drug alone consistently altered ventricular contractility compared with placebo. Ablation of reflex sympathetic tone with esmolol unmasked a negative inotropic effect for nifedipine (p = 0.03 vs. esmolol alone) but not nicardipine (p = 0.68 vs. esmolol alone). The difference between the contractility effects of nifedipine plus esmolol versus those of nicardipine plus esmolol approached statistical significance (p = 0.07). CONCLUSIONS: Totally noninvasive techniques showed a differential effect on left ventricular contractility between nifedipine and nicardipine when alterations in afterload and reflex sympathetic responses were eliminated as confounding variables. This diagnostic approach, based on the use of pharmacologic probes, should have wide applicability for assessing the direct inotropic effect of any agent, even in the presence of complex primary and secondary physiologic modes of action.

Non-invasive assessment of cardiovascular mechanics using a new, user-friendly software application.

Currently, in most non-invasive imaging laboratories, echocardiographic tracings are interpreted by "eyeballing" M-mode and 2-dimensional echocardiographic recordings. This subjective method of data analysis severely hampers the possibility of serial assessment of physiological interventions on cardiovascular disease states. Moreover, acquisition of important cardiovascular physiological data usually requires recordings of instantaneous aortic pressure and flow data that, until recently, could only be acquired invasively in the cardiac catheterization laboratory. Recently, our laboratory has developed and validated new "non-invasive" methods for the acquisition of aortic pressure and flow using calibrated subclavian pulse tracings and continuous wave aortic Doppler, respectively. With these limitations and new developments in mind, we developed new software that enables simultaneous non-invasive acquisition of left ventricular (LV) chamber geometry and aortic pressure and flow data. This new, user-friendly software in conjunction with other non-invasive tools allows non-invasive quantification of multiple cardiovascular physiological parameters. More importantly, the new software enables objective and serial assessment of multiple pharmacological interventions on various patients' disease states.